Background: Tissue factor (TF) is an initiation factor for blood coagulation, and its expression is induced on macrophages and endothelial cells during the inflammatory or immune responses. In a previous study, we reported the significance of TF expression in hepatic ischemic reperfusion injury using a rat model. Recently, tissue factor pathway inhibitor (TFPI) has been discovered, and the effect of TFPI has been assessed in vivo. In this study, therefore, we studied the effect of TFPI on hepatic ischemic reperfusion injury of the rat.
Methods: After laparotomy of Lewis rats, the branches of the hepatic artery and portal vein leading to the median, left, and caudate lobes of the liver were clamped. The liver was reperfused after 120 or 180 min of ischemia. Simultaneously, recombinant human TFPI (4 mg/kg) was injected via a superiomesenteric vein. Rats were sacrificed at 5, 12, and 24 hr after reperfusion, and liver tissues were harvested. TF expression was studied by immunohistochemical staining with the monoclonal antibody (HTF-K108).
Results: Survival rates over a 5-day period were examined after the ischemic time of 120 and 180 min. Seven of 10 rats in the 120-min ischemia group (n=10), and only 1 (10%) rat of 10 in the 180-min ischemia group (n=10) survived. However, by the treatment with TFPI, all of the rats in the 120-min ischemia group (n=10), and six rats in the 180-min ischemia group (n=10) survived (P<0.05). The serum concentrations of alanine aminotransferase (ALT) and thrombin-antithrombin complex (TAT) before ischemia were 30.0+/-2.3 IU/L and 4.7+/-1.4 ng/ml, respectively (n=5). These levels showed a peak at 3-5 hr after reperfusion (ALT: 13909+/-1900 IU/L, TAT: 30.4+/-7.0 ng/ml) (P<0.01). However, both peak levels were decreased by the treatment with TFPI (ALT: 6017+/-1290 IU/L, TAT: 5.4+/-2.1 ng/ml) (P<0.01). Although TF was strongly stained on endothelial cells and Kupffer cells accumulating to the site of the necrosis in the control group, the area of the necrosis and the grade of TF staining were significantly reduced in the TFPI-treated group.
Conclusions: These results indicated that TFPI strongly inhibited the injury of the ischemic reperfusion, and confirmed that TF played a pivotal role in the development of ischemic reperfusion injury.